Revolving bark-removing tools simultaneously biased by endless pressure-equalizing band



Sept. 15, 1959 o. c. G. WENNBERG REVOLVING BARK-REMOVING TOOLSSIMULTANEOUSLY BIASED BY ENDLESS PRESSURE-EQUALIZING BAND 3 Sheets-Sheet1 Filed June 15, 1956 IN V EN TOR. Owv CAEL Guar/w fl-w/valse Ja /N#7775 O. C. G. W OVING TO Sept. 15, 1959 ENNBERG 2,904,085

' OLS SIMULTANEOUSLY BIASED PRESSURE-EQUALIZING BAND Flled June 15 19563 Sheets-Sheet 2 INVENTOR. 0101/ (4/21. Gus-ray MAA/BEKG REVOLVINGBARK-REM BY ENDLESS United States Patent REVOLVING BARK-REMOVING TOOLSSIMUL- TANEOUSLY BIASED BY ENDLESS PRESSURE- EQUALIZING BAND Olov CarlGustav Wennberg, Karlstad, Sweden, assignor to General EngineeringCompany A.B., a corporation of Sweden Application June '15, 1956, SerialNo. 591,738 Claims priority, application Sweden June 20, 1955 3 Claims.(Cl. 144-208) In barking machines of the drum type it is common practiceto set the barking tools against the log to be barked, by means ofresilient members adapted to actuate the barking tools individually.This arrangement is generally satisfactory in the barking of straightlogs with a comparatively smooth surface, whereas logs, which arecrooked and have large or small depressions or elevations on the surfacethereof, become unevenly barked. Bark is thus left in the depressions,while the elevations are subjected to working pressures of so high anorder that the Wood might become damaged. In connection with crookedlogs, the various tools are loaded difierently, so that the toolslocated on the convex side of the log are subjected to greater forcesthan the tools which for the time being are caused to bear on theopposite side.

The present invention has for its object to obviate these drawbacks.This is made possible, above all, by an arrangernent distinguished bythe feature that the resilient pressure on the log is provided by meansof a pressure member common to two or more of the barking tools.Generally, the barking tools are uniformly distributed along thecircumference of the barking drum, and the common pressure member causesthe working pressure to be distributed alike on the various tools. It isalso provided for through the invention that the same pressure isobtained at all barking tools, independently of whether the log islocated at the center of the barking drum or not. If a crooked log movespast the barking tools, so that their engaging surfaces are moved moreor less eccentrically, this does not affect the working pressure, whichthus becomes alike on the various tools in spite of the displacement.Hereby, an improved barking quality and a more rapid and uniform feedingof the logs through the machine are obtained in turn.

The pressure member may be constructed in different ways to bring aboutthe desired working pressure. It may be resilient in itself, holders forthe barking tools being then clamped into the same. It is also possibleto arrange the pressure member as a distributor of one or more resilientforces on the various barking tools actuating the same, so that thebarking tools are actuated by resilient forces of the same magnitude. Itis also possible to make the pressure member resilient in itself whilesimultaneously causing the same to be actuated by resilient forces. a

The contrivance is advantageously provided with adjusting devices, bymeans of which the effect of the pressure member may be varied.

Further features of the invention and advantages connected therewithwill appear from the following description of a few forms of embodiment.

In the accompanying drawing, Fig. 1 is a diagrammatic representation ofa barking machine in vertical projection and partly in section. Fig. 2shows the barking drum with the barking tools viewed on line 2-2 inFig. 1. Fig. 3 represents a vertical transverse section through abarking drum that corresponds to the drum shown in Fig. 1, but showsspring pressed rollers and an endless nonelastic band for equalizingworking pressures of the barking tools;

Fig. 4 represents a fragmentary right-hand elevation of Fig. 1, butomits a tool-positioning mechanism, and shows a modification of theconstruction in Fig. 3, the endless band being elastic and its tensionbeing varied by screwactuated pressure rollers;

Fig. 5 shows a centripetal view of a detail of Fig. 4;

Fig.6 shows, in a fragmentary vertical transverse section through thedrum on the line 6-6 in Fig. 1, details of a log-actuated, tool-openingand band-tensioning device;

Fig. 7 shows a centripetal view of a detail of the arrangement of Fig.6, but includes a planar ring that shifts axially of the drum inresponse to changes in log diameter; and

Fig. 8 is a part sectional plan view of the preferred embodiment of themachine including the tensioning means appearing in Fig. 4, the meansshown in detail in Fig. 7 being removed to enable proper illustration ofother details.

As will be found from the drawing, a barking drum 1 is rotatably mountedin a housing 2, which is secured to a foundation 3. The barking drum isrotated in the housing 2 in a manner known per se by means of drivingmembers, such as a wedge belt 1a and a Wedge ring 1b (Figs. 1 and 4).Barking tools 5 are arranged on a radial flange or disk 4 on the barkingdrum 1. The barking tools are secured to, or are integral with, holdersin the form of curved arms 6 (Fig 2.), which are keyed onto shafts 7carried in bearings 8 (Fig. 1) on the disk 4. The shafts 7 extendthrough the disk 4 and carry, at the opposite side thereof, crank ortensioning arms 9, which are also keyed to the shafts 7. Studs orrollers 10, hereinafter called crank rollers, are secured to the ends ofthe crank arms 9, and extending over said rollers, is a pressure memberwhich provides or mediates the working pressure to the barking tools.

In the embodiment shown in Fig. 3, the pressure member consists of anendless band 11' running over all of the crank rollers 10. The pressureis provided by means of springs 12 adapted to actuate rods 13, which aredisplaceably mounted in holders 14 on the disk 4. The rods 13 preferablyextend radially and carry pressure rollers 15 on the inner ends thereof,said rollers bearing on the band 11', which is reeved alternately aroundthe rollers 10 and 15. In the construction shown, there are eightsprings and pressure rollers mounted in equiangular radial relation withrespect to the axis of the drum, but obviously the number of saidmembers may be greater or smaller.

In a modified construction according to Figs. 1, 4 and 6, an endlessband 11 is conceived of as being resilient in itself and consisting ofrubber, for example, in which case the springs 12 and the correspondingpressure rollers of Fig. 3 become unnecessary, the control of theresilient tension of the band 11 being obtained by adjusting devicesconsisting of screw spindles 16 threaded into nuts 17, which are securedin holders 18 on the disk 4 of the'barkingdrum. Rollers 19 are providedon the inner endsof the spindles 16, whieh'are preferably directedradially, said rollers being set against the band 11, and the outer endsof the spindles carry operating members, such as star wheels 20 (Fig.5). By the spindles 16 being screwed in with the aid of the star wheels20 the band 11 is brought under tension, the barking tools being thusset against the log with greater force.

Figs. 1, 6 and 7 show various means to facilitate opening of the barkingtools according to the diameter of the log to be barked. Such opening ofthe tools is intended to take place automatically in response to changesin log diameter, and the means for this purpose is evidenced by acomparison between the figures just mentioned.

The tool-opening contrivance consists of feeling members arranged forcooperation with the log 21 on the feeding-in side of the machine, saidfeeling members comprisinga pair of rollers 22, for example, betweenwhich the log is intended to pass when fed into the machine. The rollers22 are mounted on angular arms 23, which are in turn mounted on axles 25in floor-stands 24 laterally of the path of the logs. Said angular armsare provided with intermeshing toothed segments 26, so that they willturn simultaneously and by the same amount about the axles 25. Link rods28 are articulated to a projection on each of the angular arms and to aplate or ring 27, said link rods 28 forming a lever system together withthe angular arms. The angular arms are journaled at the plate 27 on acommon pin 29. The plate 27 is carried by brackets 30 secured to thehousing 2 and by rods 31 secured to the plate 27 (only one bracket androd being illustrated), said rods extending displaceably in saidbrackets and parallel to the axis of the barking drum. The plate or ring27 extends concentrically about the barking drum 1 and forms a planerace for rollers 32, which are mounted in arms 33 splined onto shafts34. These shafts are journalled in brackets 35 on the disk 4'of thebarking drum and actuate rackand-pinion 'gearings. Each gearing consistsof a pinion or gear wheel 36 splined onto the shaft 34 and meshing witha toothed rack 37, which is displaceably mounted at one side of the disk4 in slide bearings 38 (Fig. 6). One end of the toothed rack 37 bears ona projection 39 on a lug 40, which is secured on the crank arm 9attached to the shaft 7 of the barking arms 6.

The mode of operation of the tool-opening device is as follows: When alog 21 is fed into the machine (see the arrow 41 in Fig. 1), the foreend thereof strikes against the rollers 22, so that the angular arms 23are swung outwardly from one another and displace the plate 27 to theleft by means of the link rods 28, as shown by the arrow 42. The arms 33carrying the rollers 32 are thus caused to turn the shafts 34, in amanner such that the toothed racks 37 will be displaced by the gearWheels 36 in a clockwise direction in Fig. 6. The crank arms 9 and theshafts 7 are simultaneously turned by the toothed racks 37 in aclockwise direction in Fig. 6, whereby the arms 6 of the barking toolsare swung outwardly and the barking members proper are separated so asto leave an entrance opening of just the right size for the log (Fig.2). At this movement the band 11 running over the crank rollers on thecrank arms 9 will be strained to a suitable initial value. The barkingtools are then kept set against the log with a suitable pressure. Thepressure may be controlled by means of the adjusting devices 1620.

The advantages of the resilient means described reside, above all, inits equalizing effect on the working pressure between the barking toolsand the log subjected to barking. This effect sets in both in connectionwith local irregularities in the log surface and in connection withcrooked portions of the log. With reference to Figs. 1-3 this may beexplained in principle as follows:

For instance, if one of the barking tools 5 moves past an elevation onthe log, it will be swung outwardly, and consequently the correspondingcrank will also swing out, so that its crank roller is brought to agreater diameter. As a result of this the pressure member is tensioned,but the increase of the tension is distributed along the whole of itscircumference and thus also to the other barking tools, so that theworking pressures on them become alike.

If instead a crooked portion of the log having a constant diameter movespast the barking tools, the engaging ends of the same will be displacedfrom the concentric position relatively to the axis of rotation of thebarking drum taken by said ends, as when passing a straight log portion,to an eccentric position. This, however, does not alter the tension inthe pressure member, inasmuch as the crank rollers 10 are only caused tolie with their centers on a circle which has been displacedeccentrically relatively to that circle concentric to the axis ofrotation of the drum which they take in the initial position, or when astraight log passes between the barking tools.

A result of the uniform distribution of the resilient forces on thevarious barking tools is that the operation of the machine becomessmooth and steady, and that during the feeding'of the log between thebarking tools the latter will accurately follow the surface of the log.

A special advantage is that the arrangement may be readily supplementedso that the tension in the pressure member and thus the working pressureon the log can be controlled during the operation of the machine.

What I claim is:

1. In a barking machine a rotary drum through which a log to be barkedpasses axially, a plurality of axles supported by said drum to berotated therewith, barking tools each keyed to one of said axles, crankarms each keyed to one of said axles, and an endless flexible bandactuating a plurality of said crank arms in common to apply a resilientpressure to the tools.

2. In a barking machine, a rotary drum through which a log to be barkedpasses axially, a plurality of axles supported by said drum to berotated therewith, barking tools each keyed to one of said axles, crankarms each keyed to one of said axles, and a pressure member actuating aplurality of said crank arms in common to apply a resilient pressureto'the tools, pressure rollers mounted on said drum between said crankarms, and the pressure member comprising an endless band reevedalternately around the crank arms and the pressure rollers.

3. A barking machine comprising a rotary drum through which a log to bebarked passes axially, swingable barking tools entrained by the drum;crank arms or levers connected with said tools, said levers comprisingfirst rollers or studs; an endless band, and adjusting devices mountedon the drum for varying the tension of said band, said adjusting devicescomprising second rollers, and the band being reeved alternately aroundsaid first and second rollers. 7

References Cited in the file of this patent UNITED STATES PATENTS 70,288Swan Oct. 29, 1867 944,290 Spaak Dec. 28, 1909 2,749,952 Leagug June 12,1956 2,767,750 Stewart Oct. 23, 1956 2,779,363 Laughton Jan. 29, 19572,786,499 7 I Brundell et a1. Mar. 26, 1957

